What does 1 Corinthians 14:22 mean?
Paul is summing up his case for why the use of the gift of prophecy in the meetings of the church is better than the use of the gift of tongues. He lays out a seemingly straightforward principle: Tongues are a sign for unbelievers. Prophecy is a sign for believers.Unfortunately, the explanation of this principle is not easily followed. In the following verses, Paul will show how the misuse of the gift of tongues may, in fact, drive unbelievers away from the church. In contrast, the proper use of the gift of prophecy may bring them to faith in Christ.
It's possible that Paul is connecting this statement to the previous verse, in which he quotes from Isaiah 28. In that passage, unbelieving Israelites were to be driven more deeply into unbelief by hearing God's message in foreign tongues. Those alien languages would ensure that they did not, in fact, hear what God would say to them. In that sense, the use of uninterpreted tongues in the Corinthian church may also be the "sign" that drives an unbeliever further from faith in Christ.
The use of the gift of prophecy, though, may be a "sign" to the believers in Corinth as they see unbelievers respond to it with repentance and newfound faith.
For unbelievers, then, the gift of tongues is a negative sign. For believers, prophecy is a positive sign. For all, the use of the gift of prophecy to communicate the clear message of the Lord is far superior than the display of the gift of tongues when no one is available to interpret.